linux-kernel - [PATCH 3/3] timer_migration: Improve tracing

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Message-Id: <20240621-tmigr-fixes-v1-3-8c8a2d8e8d77@linutronix.de>
Date: Fri, 21 Jun 2024 11:37:08 +0200
From: Anna-Maria Behnsen <anna-maria@...utronix.de>
To: Frederic Weisbecker <frederic@...nel.org>, 
 Thomas Gleixner <tglx@...utronix.de>, linux-kernel@...r.kernel.org
Cc: Anna-Maria Behnsen <anna-maria@...utronix.de>
Subject: [PATCH 3/3] timer_migration: Improve tracing

Trace points of inactive and active propagation are located at the end of
the related functions. The interesting information of those trace points is
the updated group state. When trace points are not located directly at the
place where group state changed, order of trace points in traces could be
confusing.

Move inactive and active propagation trace points directly after update of
group state values.

Signed-off-by: Anna-Maria Behnsen <anna-maria@...utronix.de>
---
 kernel/time/timer_migration.c | 11 +++++------
 1 file changed, 5 insertions(+), 6 deletions(-)

diff --git a/kernel/time/timer_migration.c b/kernel/time/timer_migration.c
index f55be5411ad9..41ea48d08c65 100644
--- a/kernel/time/timer_migration.c
+++ b/kernel/time/timer_migration.c
@@ -656,6 +656,8 @@ static bool tmigr_active_up(struct tmigr_group *group,
 
 	} while (!atomic_try_cmpxchg(&group->migr_state, &curstate.state, newstate.state));
 
+	trace_tmigr_group_set_cpu_active(group, newstate, childmask);
+
 	if (walk_done == false)
 		data->childmask = group->childmask;
 
@@ -673,8 +675,6 @@ static bool tmigr_active_up(struct tmigr_group *group,
 	 */
 	group->groupevt.ignore = true;
 
-	trace_tmigr_group_set_cpu_active(group, newstate, childmask);
-
 	return walk_done;
 }
 
@@ -1305,9 +1305,10 @@ static bool tmigr_inactive_up(struct tmigr_group *group,
 
 		WARN_ON_ONCE((newstate.migrator != TMIGR_NONE) && !(newstate.active));
 
-		if (atomic_try_cmpxchg(&group->migr_state, &curstate.state,
-				       newstate.state))
+		if (atomic_try_cmpxchg(&group->migr_state, &curstate.state, newstate.state)) {
+			trace_tmigr_group_set_cpu_inactive(group, newstate, childmask);
 			break;
+		}
 
 		/*
 		 * The memory barrier is paired with the cmpxchg() in
@@ -1326,8 +1327,6 @@ static bool tmigr_inactive_up(struct tmigr_group *group,
 	if (walk_done == false)
 		data->childmask = group->childmask;
 
-	trace_tmigr_group_set_cpu_inactive(group, newstate, childmask);
-
 	return walk_done;
 }
 

-- 
2.39.2